Hybridization betweenHelicoverpa armigeraandHelicoverpa assulta(Lepidoptera: Noctuidae): development and morphological characterization of F1hybrids

Abstract

AbstractReciprocal hybridizations betweenHelicoverpa armigera(Hübner) andHelicoverpa assulta(Guenée) were studied. The cross between females ofH. armigeraand males ofH. assultayielded only fertile males and sterile individuals lacking an aedeagus, valva or ostium bursae. A total of 492 larvae of the F1generation were obtained and 374 of these completed larval development and pupated. Only 203 pupae were morphologically normal males, the remaining 171 pupae were malformed. Larvae and pupae that gave rise to morphologically abnormal adults exhibited longer development times. Sterility was not only associated with malformed external sex organs, but also a range of abnormalities of the internal reproductive system: (i) loss of internal reproductive organs, (ii) with one to three copies of an undeveloped bursa copulatrix; or (iii) with one or two undeveloped testes. Normal male hybrid adults showed higher flight activity in comparison with males of both species. In contrast, the cross between females ofH. assultaand males ofH. armigerayielded morphologically normal offspring (80 males and 83 females). The interaction of the Z-chromosome fromH. assultawith autosomes fromH. armigeramight result in morphological abnormalities found in hybrids and backcrosses, and maternal-zygotic incompatibilities might contribute to sex bias attributed to hybrid inviability.